Same Surname, Different DNA - some potential medieval explanations

Why are there so many different genetic signatures associated with a single surname? There are a multitude of reasons for why this may be so, and I discuss many of them in an earlier article here. 

However, in this article I want to focus on those potential causes that date back to the time of the Irish clans, prior to the Cromwellian conquest of Ireland. And this takes us back in time to a period prior to the demise of the Old Gaelic social system, a system that had been guided for centuries by a comprehensive legal system known as Brehon Law. (1) It recognised divorce, (some) equal rights for women, and defined offences and punishments in meticulous detail. The end of this system was signalled by a Proclamation of James I in 1603, which brought the Irish people under the "protection" of the English Crown.

Brehon Law operated in Ireland from Celtic times to the early 1600s, a period of over 2000 years. 
Brehons were arbitrators rather than judges, and the post was open to women and men.
(from https://www.courts.ie/history-law-ireland#brehon)

The Creation of Surnames

Brehon Law was well-established in Ireland by the time surnames were introduced (roughly 1000 years ago on average for the O surnames, and 850 years ago on average for the Mac surnames). Most Irish surnames arose from an ancestor's forename (e.g. descendants of Chief Conor became O'Connor). Some forenames were very common (like Conor) and thus the same surname arose in several different places, over several hundred years, but from completely different origins. And hence the progenitors had completely different Y-DNA signatures, and were not closely related to each other. There are at least six separate O'Connor clans/septs recorded in Woulfe's surname dictionary (2) ... and in fact there are 34 distinct genetic subgroups in the O'Connor DNA Project (so far). Thus, one explanation for different genetic groups being associated with the same surname is that many surnames had multiple origins, each of them distinct from the others, and each with their own unique Y-DNA signature.

In 1916 for example, T J Westropp, the famous antiquarian, described the Limerick O'Malley's as one of several "petty tribes ... rather families than septs". (3) And indeed, there may have been several of these "families" within the Limerick area as there are now 6 subgroups under L226 in the O'Malley DNA Project, all with recorded (or likely) Limerick origins. I'll give some more examples in relation to the O'Malley surname below.

The Translation of Surnames

Another possible explanation for different Y-DNA signatures being associated with the same surname is the anglicisation of surnames, a process aimed at forcing the Irish to conform to English culture that saw surnames being translated from the Irish language form into an approximate English language form. (4) This long-term process was a key part of the English colonisation of Ireland and picked up speed during the lifetime of Grace O'Malley (1530-1603) with the passage of new laws under Henry VIII (1537) that essentially labelled the use of the Irish language as a sign of opposition to the English Crown. (5) Serious problems arose during the process of translation. Some surnames in Irish with completely separate origins were anglicised to the same English version. Thus A and B both became anglicised to X.  And so genetically we find that there are X's with an A genetic signature and X's with a B genetic signature - two genetically distinct groups with "the same" surname (or variants thereof). 

Conversely, anglicization also helps explain why there are so many variants of the O’Malley surname. There are several examples on the public Results Page of people who have the same Y-DNA but different surname variants (Malley, O'Malley, Maley, Melia, Malia, O'Meally, etc).

The Switching of Surnames

There were several important aspects of the Old Gaelic social system that could explain why different genetic signatures became associated with (for example) the O'Malley surname.

Some people switched their surname to that of the chief as a sign of their loyalty or fealty. (6) In this way, surnames of less powerful families "gravitated" toward more powerful families. Such a process has been termed "surname gravity" by leading medieval Irish academic, Bart Jaski (see his GGI2019 presentation here). Grace O'Malley herself (the famous Pirate Queen of Mayo) may have commanded such respect even though she was never formally a clan chief. In her biography of Grace, (7) Anne Chambers describes how Grace became “a matriarch, not merely of her own followers and extended family, but of neighbouring clansmen, whose chieftains had either died in the numerous conflicts of the period, or who had abandoned their obligations to protect their dependent followers.” Some of these refugees may have adopted the O'Malley surname as a mark of respect, gratitude and loyalty to Grace.

Strangers could be given the honour of being adopted into a clan (a form of citizenship) in recognition of their contribution to the clan community. (8) Some of these may also have had the O'Malley surname bestowed upon them (for example).

Some marriages resulted in the husband adopting the surname of the wife, especially if she was of higher social standing than he was. An apt example of this is the case of Oliver Cromwell, who should really have been called Oliver Williams. However, in 1497, his great great grandfather (Morgan Williams) had married Katherine Cromwell, sister of Thomas Cromwell, chief minister to Henry VIII. Morgan and Katherine’s three sons took the surname Cromwell in honour of their famous maternal uncle. Thus, Oliver Cromwell carried the Cromwell surname but Williams Y-DNA. Some family members later reverted to the surname Williams in order to distance themselves from their contentious cousin, thus executing a double-surname switch. (9) 

Some women retained their maiden name. After the death of her second husband (Richard Bourke) in 1583, Grace O'Malley herself used her maiden name (Grany Ni Mailly) in her exchanges with Queen Elizabeth I who addressed her as such in her replies. (10)

Marriage, Sex ... and possibly Infidelity?

Under Brehon Law, marriage and sexual relations were approached very differently compared to today (and very very differently compared to the Victorian attitudes of 100-200 years ago). Ireland under Brehon Law was a much more sexually permissive society than one might imagine. It might be tempting to think that medieval society was like The Swinging Sixties, but better regulated and with everyone "on board", but promiscuity was frowned upon (at least female promiscuity), and was among the types of behaviour most frequently censured in women. (11) Furthermore, the introduction of inheritance by primogeniture (i.e. to the eldest son) led to a gradual change in sexual permissiveness in the 1600s, particularly for the landed classes. (12)

Most marriages were secular marriages based on the ancient customs - few people were married in church (13). Divorce was easy (for both men and women) and it was usual for the upper classes to have a string of different spouses. (13) This created an environment where the same surname could become associated with different types of Y-DNA.

Marriages usually started out as trial marriages for "a year and a day". (8) If at the end of the period, the couple were happy to continue as husband and wife, then they got legally married. But if they did not feel they could live together, they separated. Grace O'Malley famously did this with her second husband, shouting "Richard Bourke, I dismiss you" from the ramparts of his castle where she had installed herself and her followers, and locked him out. He can't have been very pleased to have lost a wife and a castle on the same day. (7)

Interestingly, if a couple separated at the end of the trial marriage, any children born to them during that time became part of the woman's kin (and thus presumably bore the name of her kin). (8) Thus if an O'Malley woman had a child during the trial period and then decided not to continue to legal marriage, the child would become an O'Malley but would carry non-O'Malley Y-DNA. Thus different Y-DNA was introduced to the wider O'Malley Clan.

Polygamy was allowed and it was common to have two or more wives. However, the term "wife" was more applicable to the first wife (the chief or principal wife). Subsequent wives had fewer rights than the first wife and might perhaps be more aptly considered as "concubines". (8,11,12,13)

The Brehon Laws refer to nine forms of sexual union. (11) The first three roughly equate with our modern concept of marriage, and the next four could be more akin to casual sex (referred to as "affinity" or "affiliation"), and the last two cover rape and insanity. The nine forms of sexual union are:

1. when a man and woman get married and bring equal property or wealth to the marriage
2. a marriage where the woman brings little or no wealth / property / goods to the marriage
3. a marriage where the man brings little or no wealth / property / goods
4. when a man visits a woman at her home, and with her kin’s consent
5. when a woman freely goes away (elopes?) with a man, but without her kin’s consent
6. when a woman allows herself to be abducted, and without her kin’s consent
7. when a woman and man secretly visit each other, without her kin’s consent
8. union by rape
9. union of two insane people

Why was it necessary to create these categories of sexual union? The reasons are probably complex and our understanding of them incomplete, but they had applicability with regard to the rights of children to inherit their father's estate, the inheritance rights of the different types of "wife", the division of property and wealth following divorce, and the legal status of the woman (i.e. under whose rule she came, how much fine was payable if she was killed or raped, and how much fine was due and payable by whom if she committed a crime). 

In cases of rape, forced abduction, or where the woman did not consent to the sexual union, heavy fines were levied on the offender, and the responsibility for raising any child of the union fell on the offender and his kin. (8,11) This applied whether the woman was married, unmarried, a servant or a slave. (11)

Sex with servants was apparently commonplace, both heterosexual and homosexual. (8,14) The children of any such union may have become the father's responsibility, and may have adopted his surname, but this is unclear and would have depended on the circumstances and whether the mother had any rights.

In certain circumstances, the woman alone was responsible for rearing a child (presumably with the help of her own kin). These included if she was a prostitute, or if the father was a stranger / alien (cú glas), a slave, a satirist, a man expelled by his kin; a dependent son, who impregnated her without his father's permission; or a priest who later repented. What surname the child took in these circumstances is not clear, but no doubt in many instances a son would have retained the mother's surname, and in this way, the particular surname could have become associated with different Y-DNA.

Legal documents often consisted of large text (representing the original law) with explanatory text and interpretations in small print. The above is a detail from RIA MS 23 Q 6, p33.
From https://www.ria.ie/news/library-library-blog/brehon-law-manuscripts-reunited-galway-2020-european-capital-culture 

Divorce & Separation

Brehon Law allowed for women to divorce their husbands under specific circumstances, (8,11,13,14,15) including:

• if he tricked her into marriage through sorcery
• if he failed to support her
• if he hit her and left a (permanent?) mark
• if he insulted her in public
• if he spread a false story or satire about her
• if he discussed their sex life with others
• if he became too fat to have sex
• if he was impotent
• if he preferred to lie with boys
• if he rejected her for another woman
• if he entered the priesthood
• if he took a second "wife" without her knowledge (was this akin to our current concept of "infidelity"? Also, if he took a second wife/concubine with the knowledge of his first wife, would this then not be considered infidelity? In other words, you could do what you wanted as long as you told your spouse in advance??)
  

Men also had grounds for divorcing a wife including: 

• "infidelity" (not further defined)
• persistent thieving (... but occasional thieving was okay?)
• bringing shame on her husband's honour
• inducing an abortion
• smothering a child
• not being able to produce breast milk because of sickness

Furthermore women who left their husbands without just cause were stripped of their rights, denied shelter, and treated as outcasts. (8,11,14) There is no mention of this same treatment being inflicted on men, so the gender equality scales were not exactly balanced.

Another interesting example of grounds for divorce was if the couple were related by "affinity" i.e. if either party had had sex at any time in the past with a relation of their spouse, out to the level of third cousins. (13) Under Canon Law, the medieval church forbade marriage if the couple were 3rd cousins or closer, or if either had been married or had had sex (even once) with any of their prospective partner's relatives, out to the level of 3rd cousin. (How did they figure this out? Did they sit down and go through each other's family trees? Sounds like if you wanted to get married properly, you had to be a genealogist.)  If either party was previously married to a relative of the other (within the proscribed range), a papal dispensation would be necessary for the new marriage to be allowed and to be considered valid. Given society's relaxed attitude to sex, and the tendency to marry one's own kinfolk, it is likely that many marriages would not have been considered "valid"  in the eyes of the Church, but the couple managed to sail under the ecclesiastical radar ... or alternatively, could divorce each other at the drop of a hat. (12,13)

There were specific circumstances in which a couple could separate without being fined or penalised. Eleven such scenarios are listed in one book of Brehon Laws (Heptad 53) and these include death, entering the priesthood, and a variety of situations associated with temporary separation, such as going on a pilgrimage, searching for a far-off friend, going on a sea voyage, being in a revenge attack party, or being sick and requiring care away from home. But the most relevant situation with regard to Y-DNA is where the husband is infertile, the wife does not wish to divorce him, and instead goes away "to seek a child" by another man. The resultant child was treated as that of her husband - and in such a situation, the child would carry the husband's name but another man's Y-DNA. (11, p75)

Illegitimacy

Under Brehon Law, there was no concept of "illegitimacy" as we know it today  - every child was cared for by kin, no matter what their origins, be it a legal marriage, a casual fling, or an illicit tryst. In addition, there was apparently no social stigma, no concept of "the fallen woman" who had become pregnant "out of wedlock". Their attitude to such things was very different to that of (for example) 20th century Ireland. (8,11,13,14)

And these children, born outside of legal marriage, had equal rights to inherit their biological father's estate. (11,13) Just a few years ago (in 2022), legislation was passed by the Irish parliament that restored this prior right that such illegitimate children would have enjoyed under Brehon Law. The only thing that "out-of-wedlock" children were barred from doing was being a priest, apparently because "the child carried the sin of the mother".

In medieval Ireland, sometimes entertaining the guests went a lot further than just having them over for dinner. This is evidenced by the custom of "Naming" of children. In this case, a married woman, usually on her deathbed, would reveal that one of her sons had in fact been fathered by a man other than her husband, and usually quite a famous man with status, wealth and property. This newly illegitimized son thus became entitled to inherit the estate of his new father, but could also fall under his protection (thus securing his safety when his mother was no longer around to protect him). There are numerous contemporary examples of these "named children" and some of them (or their own children) became clan chiefs (e.g. in the latter half of the 1500s, James Meagh became chief of the O'More's, and Feardorcha O'Neill's son Hugh O'Neill became Earl of Tyrone). (13) Undoubtedly some of these "naming" events were pure lies, but this is another example of how different Y-DNA could become associated with a particular surname.

Adoption & Fosterage

Fosterage was very common in medieval Ireland. Parents would give a child for fosterage to another family if they wanted to forge strong links with that family, or if they wanted their child to learn a profession. The period of fosterage was usually up to to seventeen years old for boys, and up to 14 years old for girls (after which they became nuns or wives). (11)

If a child was adopted (by a childless couple, for example), it is likely that they would have carried the surname (but not the Y-DNA) of the adoptive father. But if a child was fostered, then they probably retained the surname (and Y-DNA) of their biological father. The only circumstance where the fostered child might adopt the name of the foster father, might have been if the natural father died while the child was being fostered.

The Election Process

The way clan chiefs were elected changed considerably over time. The Irish clans operated under Brehon Law and the system of Tanistry, whereby a successor for the chieftainship would be chosen from relatives within the derbfine, i.e. direct male line relatives of the chief out as far as "the fifth degree of relationship" (roughly second cousins). (13) As a result, the Y-DNA signature of the clan chief should have remained relatively unchanged down through the generations, because subsequent clan chiefs would be related to him on his direct male line. However, it is possible that the DNA of the Clan Chief may have varied from time to time, if a DNA switch had occurred on the direct male lines of relatives within the derbfine. And thus (for example), the various genetic groups with Mayo origins that we see in the O'Malley DNA project today, may have been associated (at one time or another) with an O'Malley chief that carried their DNA signature. 

This Irish system of Tanistry was eventually replaced when the English system of primogeniture was foisted upon the clans (including the O'Malley's) following the Composition of Connaught in 1585. (16,17) Thereafter, the role of chief should have been passed from father to eldest son (the law was not always obeyed), thus probably reducing the opportunity for different DNA signatures to be associated with the role of clan chief.

Summary

So, to recap, the potential medieval causes for different genetic signatures being associated with the same surname may have included the following ...

1. multiple origins for the same surname
2. anglicisation of Irish surnames to English approximations
3. switching surname as an act of fealty / loyalty ("surname gravity")
4. having your surname switched as an honour / distinction bestowed by a clan
5. changing your surname to that of your higher status wife
6. being the child of failed trial marriage (and taking the mother's surname)
7. the child being raised by the mother on her own (and taking the mother's surname)
8. the wife being impregnated by another man if her husband was infertile
9. a child in fosterage adopting the name of the foster father following the death of his biological father
10. being a "named child"(i.e. the result of a union with a man of high status)

Maurice Gleeson

May 2024

An earlier version of this article appears on the O'Malley DNA Project blog here.

Sources & Links

1) History of the Law in Ireland. Available at the website of The Courts Service of Ireland.

2) Woulfe, Patrick. Sloinnte Gaedheal is Gall: Irish Names and Surnames, collected and edited with explanatory and historical notes (1923). Available at https://www.libraryireland.com/names/contents.php

3) Westropp, T.J. (1916) The antiquities of Limerick and its neighbourhood. Dublin: Hodges Figgis & Co. Available from the Archive.org website here. Note that pages 81 and 140 are missing from this version but can be found in this alternative version on the AskAboutIreland website here.

4) Murphy, P. The Anglicization of Ireland: A Model for the Linguistic Imperialist? Available online here.

5) Crowley, AE (2016) Language, Politics and Identity in Ireland: a Historical Overview. In: Hickey, R, (ed.) Sociolinguistics in Ireland. Palgrave Macmillan , London , pp. 198-217. ISBN 978-1-137-45347-1

6) Clan FAQs at https://www.scotclans.com/pages/clan-faqs

7) Chambers, A (2009, 7th edition). Grace O'Malley: The Biography of Ireland's Pirate Queen 1530–1603. Gill Books. Available from http://www.graceomalley.com/

8) Kerrigan, J (2020) Brehon Laws: The Ancient Wisdom of Ireland. Free Kindle edition available here.

9) Castlelow, E. Oliver Cromwell. Biographical article at Historic UK website available here.

10) Trowbridge, B (2016) Meeting Grace O’Malley, Ireland’s pirate queen. This article includes digital images of Grace's petition to Queen Elizabeth I (Catalogue reference: SP 63/170 f. 204) as well as the 18 "interrogatories" and her responses (SP 63/170 f. 201-202). Available at The National Archives blog.

11) Kelly, F (1988, reprinted 2016) A Guide to Early Irish Law. School of Celtic Studies, Dublin Institute of Advanced Studies. Available from DIAS here.
Prof Fergus Kelly is a Senior Professor in the School of Celtic Studies at the Dublin Institute for Advanced Studies (DIAS).

12) Simms, K (1975) The Legal Position of Irishwomen in the Later Middle Ages. Irish Jurist, vol.10, pp96-111. Available to read or download here.
Katharine Simms is Senior Lecturer in Medieval History in the School of Histories and Humanities, Trinity College Dublin.

13) Nicholls, K. (2003, 2012 digital reprint) Gaelic and Gaelicised Ireland in the Middle Ages. The Lilliput Press. Kindle Edition available from Amazon here. 
Kenneth Nicholls is a former Professor of History at University College Cork.

14) Duggan, C (2013) The Lost Laws of Ireland. Glasnevin Publishing. Kindle Edition. Paperback edition available here.

15) Ginnell, L (1898, reprinted 2011) The Brehon Laws: a Legal Handbook. Read Books Ltd.. Kindle Edition available from Amazon here. Also, freely available from the LibraryIreland website here.
Laurence Ginnell (1852-1923) was an Irish nationalist politician, lawyer and Member of Parliament (MP).

16) Cunningham, B (1984) The Composition of Connacht in the Lordships of Clanricard and Thomond, 1577-1641. Irish Historical Studies, Vol. 24, No. 93 (May 1984), pp. 1-14. Available online here.

17) McInerney, L (2011) The Composition of Connacht: an ancillary document from Lambeth Palace. North Munster Antiquarian Journal vol. 51. Available online here.